Mn掺杂TiO_2纳米材料的制备及可见光催化降解水中腐殖酸

Preparation of Mn doped TiO_2 nanomaterials and their visible-light photocatalytic performance for degradation of humic acid

以钛酸正丁酯为钛源,MnSO_4为锰源,采用溶胶-凝胶法,制备Mn-TiO_2光催化剂。经扫描电镜(SEM)、X射线粉末衍射(XRD)、光电子能谱(XPS)、紫外-可见漫反射(UV-vis DRS)等手段进行表征,同时通过对水中腐殖酸(HA)的降解实验,探讨不同煅烧温度下制备Mn-TiO_2的可见光催化性能。结果表明,在350~500℃煅烧下制备的Mn-TiO_2均为锐钛矿型,其光响应范围可不同程度拓宽到可见光区;煅烧温度是影响可见光催化活性的重要因素,过高或过低都不利,400℃煅烧制备的Mn-TiO_2催化剂可见光活性最佳;投加此催化剂1 g·L^(-1),对初始浓度5 mg·L^(-1)的HA水溶液可见光反应240min后,降解率达75.1%,且光催化反应过程符合准一级动力学,其表观速率常数为0.006 6 min^(-1)。

Mn-TiO2 photocatalyst was synthesized by a sol-gel method using the precursors of tetrabutyl titanate and manganese sulfate. The prepared samples were characterized by scanning electron microscopy（ SEM）,Xray diffraction（ XRD）,X-ray photoelectron spectroscopy（ XPS） and UV-vis diffuse reflectance spectroscopy（ DRS）. The Mn-TiO2 nanomaterials synthesized at different calcination temperatures were evaluated as photocatalysts for the degradation of humic acid（ HA） in the visible light range. It was found that Mn-TiO2 photocatalyst was identified as the anatase phase when the calcination temperature was in the range from 350 to 500 ℃,and its response could be extended to the visible light region. Furthermore,the calcination temperature played an important role in the photocatalytic activity,and the 400 ℃ enabled the best photocatalytic performance. A degradation rate of 75. 1% was achieved after 240 minutes with 1 g·L^-1of Mn-TiO2 when the initial concentration of HA is 5 mg·L^-1. The photocatalytic degradation process followed pseudo-first order kinetics with the reaction rate constant of 0. 006 6 min^-1.